Legislative initiatives have provided students with disabilities the opportunity to receive instruction and participate in the general education setting with their nondisabled peers. The content and frequency of professional development activities for the general education teachers in inclusion classrooms have often been overlooked. Consequently, many general education teachers are still uncertain about their attitudes and competency within inclusive environments. This quantitative correlational study examined the relationship between professional development, general education teachers' sense of efficacy, and attitudes toward the inclusion of students with disabilities. The guiding question examined the impact of professional development on teachers' sense of efficacy and attitude towards inclusion. The theoretical framework of the study was based on the theory of transformational learning, which is concerned with interpreting meaning from new knowledge as a guide to action. Study participants included 98 general education teachers of students with disabilities in inclusive environments. Data were collected on teachers' professional development history, efficacy, and attitude toward inclusion using validated instruments including, Scale of Teacher Attitude Toward Inclusive Classrooms, Teacher Sense of Efficacy Scale and a researcher-designed professional development survey. Results from Spearman's rho test (r = 0.44, p = 0.001) revealed a direct relationship between professional development, teachers' attitudes and sense of efficacy. This study has the potential to contribute to positive social change by providing a better understanding of strategies necessary to support successful inclusive practices and programs for general education teachers of inclusion of students with disabilities. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]